The technology of hearing aids has come a long way since the versions of the 1960's that were the size of a portable cd player; see Digital Hearing Aids - the Way of the Future for more information on the receiving part of a "raisin."
John had trained his raisin using the works of John Stuart Mill. Apparently, the raisin is intelligent on its own, not just in contact with the network.

A sample quote from JS Mill:

"Eccentricity has always abounded when and where strength of character has abounded; and the amount of eccentricity in a society has generally been proportional to the amount of genius, mental vigor, and moral courage which it contained."

An interesting analogue to this idea is the "Green Bullet" from Ray Bradbury's Fahrenheit 451, published in 1953.